Teeth

Question 1

Homodont

Answer 1

One type of tooth (many non-mammals)

Question 2

Heterodont

Answer 2

different types of teeth (many mammals)

Question 3

T/F: molars are only found in adults

Answer 3

True

Baby animals do not have molars

Question 4

T/F: both baby and adult animals may have premolars

Answer 4

True

Both babies and adults have premolars

Question 5

Which bones are mammal teeth found in?

Answer 5

• Incisive bones
• Maxilla
• Mandible

Question 6

Diphyodont

Answer 6

has baby and adult teeth

Question 7

Hypsodont

Answer 7

high crowns e.g. horses

Question 8

Brachydont

Answer 8

low crowns (relative to the overall tooth) e.g. dogs

Question 9

Role of incisors

Answer 9

• Nibbling
• Grooming
• Cutting

Question 10

Role of canines

Answer 10

• Grasping
• Fighting/defence
• Stabbing
• Toxin injections (some shrews/voles)

Question 11

Roles of premolars and molars

Answer 11

• Crushing
• Shearing
• Gripping
• Grinding

Question 12

Diastema

Answer 12

Gap between incisors and cheek teeth; typically found in herbivores

Question 13

Describe jaw action in carnivores

Answer 13

• Move jaw sideways to engage teeth
  
  • Pterygoideus muscles
  • The muscles to move jaw sideways don’t need to be strong because the food is put in the right place before biting down
• Close jaw to shear/crush
  
  • Masseter and temporalis musles
  • These muscles need to be very strong

Question 14

Describe jaw action in omnivores

Answer 14

Combined crush/grind action

Question 15

Describe jaw action in herbivores

Answer 15

• Opposite to carnivores:
• Jaw is closed first around herbage (masseter)
• Then jaw is moved sideways whilst being held closed
• This allows the grinding of plant material to break down cells
• Pterygoideus muscles are large as they are working under load, equalled by masseter muscles

Question 16

Lophodont

Answer 16

Structure of teeth in odd-toed herbivores

Question 17

Selenodont

Answer 17

Structure of teeth in even-toed herbivores

Question 18

Describe secodont arrangement of teeth

Answer 18

• e.g. carnivores
• Staggered teeth good for gripping hard and soft round objects
• Carnassial teeth overlap as the jaw closes to create cutting/scissor action

Question 19

Where is enamel in herbivore teeth?

Answer 19

• Enamel is inside the tooth, covered by cement.

Question 20

1

Answer 20

Crown: visible (supragingival) region of the tooth. Consists of smooth, hard enamel and hard dentine.

Question 21

2

Answer 21

Enamel

• Hardest known biological substance outside of limpets
• Acellular once formed so cannot be repaired if damaged
• Mostly made of hydroxyapetite
• Dissolves in acid e.g. coca cola

Question 22

Dentine

Answer 22

living tissue within the pulp cavity. Contains odontoblasts with processes in dentinal tubules.

Question 23

Primary dentine

Answer 23

most of dentine, formed as the tooth grows.

Mineralised collagen

Question 24

Secondary dentine

Answer 24

Grows slowly

Formed after tooth eruption

Makes the pulp cavity smaller

Question 25

**Tertiary dentine**

Answer 25

formed in reaction to damage Has a irregular structure that helps it fill damage

Question 26

What substances overlie dentine?

Answer 26

Enamel and cement.

Question 27

**Labial**

Answer 27

Lateral/cheek side

Question 28

**Lingual**

Answer 28

medial side of mandibular teeth

Question 29

**Palatal**

Answer 29

Medial side of maxillary teeth

Question 30

**Mesial**

Answer 30

Rostral side

Question 31

**Distal**

Answer 31

Caudal side

Question 32

**Occlusal**

Answer 32

meeting surface of teeth

Question 33

**Cusps**

Answer 33

raised parts of the occlusal surface

Question 34

**Grooves**

Answer 34

indented parts of the occlusal surface

Question 35

**Apical**

Answer 35

towards the tooth root

Question 36

**Coronal**

Answer 36

towards the tip of the crown of the tooth.

Question 37

**Periodontium** and its role

Answer 37

* Role is to attach, support and protect the tooth and jaw

Question 38

**Gingiva** and its role

Answer 38

* Squamous epithelium forming a dense fibrous layer closely bound to the periosteum * Reflects on the CEJ to form the **gingival sulchus** (risky pocket that needs to be kept clear) * This is the site where gingivitis starts

Question 39

What is cementum a.k.a. cement?

Answer 39

* Similar to bone, peripheral to dentine or enamel * Provides site of attachment for periodontal fibres * Completely covers herbivores

Question 40

Difference between cement in carnivores and herbivores

Answer 40

* In carnivores, cement does not cover enamel * In herbivores, cement grows with the tooth (as they continuously erupt) as it left on the outside, overlying the enamel

Question 41

What gets worn away slowest on herbivores teeth (dentine, cement or enamel)?

Answer 41

* Dentine and cement get worn away quicker than enamel * This leaves enamel ridges on the teeth which are good for grinding

Question 42

**Periodontal ligament**

Answer 42

series of angled collagen fibres that support the tooth, act like a shock absorber and spreads the load into the whole socket.

Question 43

What does the tooth root consist of?

Answer 43

Consists of * Cementum * Dentine * Root canal * Apex-apical delta Teeth can be single/multi-rooted.

Question 44

Describe the structure of a carnivore's tooth root

Answer 44

Dentine root covered by enamel Compare to herbivores, who have enamel all the way down to the bottom

Question 45

Types of tooth root

Answer 45

* **Closed**: the root apex has closed off * The tooth erupts slowly and continuously (horses, cattles) or erupts to a set height (dog) * **Open**: the root apex is open, so the tooth continually grows and erupts e.g. rodent incisors Remember that growth and eruption are different things.

Question 46

Describe carnivores' tooth eruption

Answer 46

Once teeth have finished growing, they erupt to a certain height and stop.

Question 47

Describe horses' tooth eruption

Answer 47

* Once teeth have finished growing, they erupt to a certain height and stop.

Question 48

1

Answer 48

Wolf tooth

Question 49

2

Answer 49

Diastema

Question 50

3

Answer 50

First incisors

Question 51

4

Answer 51

Second incisors

Question 52

5

Answer 52

Third incisors

Question 53

6

Answer 53

Canines

Question 54

7

Answer 54

Second premolars

Question 55

8

Answer 55

Fourth premolars

Question 56

9

Answer 56

First molars

Question 57

10

Answer 57

Third molars